Influence of Catalyst Acidity on the Hydrogenation\nand Dimerization of Conjugated Olefins over Supported NiMoS Catalysts
Bibliographic record
Abstract
The\nhydrogenation and dimerization of isoprene and 4-methylstyrene\nover supported NiMoS catalysts have been studied under conditions\nrelevant to the hydrogenation of Canadian oil sands naphtha, during\nwhich the undesired dimerization of conjugated olefins, present in\nnaphtha, is known to occur. NiMoS was dispersed on SiO<sub>2</sub>–Al<sub>2</sub>O<sub>3</sub> supports with varying Si/Al contents\nto determine the impact of the catalyst acidity on the dimerization\nreactions. The reactions were carried out in a microscale trickle-bed\nreactor operated at 200–250 °C, 3.4 MPa H<sub>2</sub>,\nand liquid hourly space velocity (LHSV) of 2–4 h<sup>–1</sup> for reaction periods of 3 days of continuous operation. The acidity\nof the NiMoS/Al<sub>2</sub>O<sub>3</sub> catalyst, measured by NH<sub>3</sub> temperature-programmed desorption and pyridine adsorption\ndiffuse reflectance infrared Fourier transform spectroscopy, was lower\nthan that of the NiMoS/SiO<sub>2</sub>–Al<sub>2</sub>O<sub>3</sub> catalysts, which increased with increased SiO<sub>2</sub> content up to 20 wt % SiO<sub>2</sub>. The results showed that dimer\nformation correlated with the acidity of the catalysts. The dimer\nyield on the sulfided supports without NiMoS was about 40% of the\nyield observed on the NiMoS/SiO<sub>2</sub>–Al<sub>2</sub>O<sub>3</sub> catalysts. The NiMoS catalysts showed stable activity over\n3 days of continuous operation, whereas the sulfided supports deactivated\nrapidly because of low hydrogenation activity. Addition of 3 wt %\nNaOH to the NiMoS/S10 catalyst neutralized 60% of the acid sites,\nresulting in a 50% drop in dimerization yield.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.004 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".